[MySQL] Unknown collation utf8mb4_unicode_520_ci

[MySQL] Unknown collation utf8mb4_unicode_520_ci

ERROR 1273 (HY000) at line 25: Unknown collation: 'utf8mb4_unicode_520_ci'

CREATE TABLE `wp_commentmeta` (
  `meta_id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
  `comment_id` bigint(20) unsigned NOT NULL DEFAULT '0',
  `meta_key` varchar(255) COLLATE utf8mb4_unicode_520_ci DEFAULT NULL,
  `meta_value` longtext COLLATE utf8mb4_unicode_520_ci,
  PRIMARY KEY (`meta_id`),
  KEY `comment_id` (`comment_id`),
  KEY `meta_key` (`meta_key`(191))
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_520_ci;
/*!40101 SET character_set_client = @saved_cs_client */;

Swapping
    utf8mb4_unicode_520_ci => utf8_general_ci

ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_520_ci;
=>
ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_general_ci;